Because a giga-coaster is specifically defined as smaller than that one: "Enthusiasts use the term to apply to a roller coaster with a drop of 300 to 399 feet,

Because a giga-coaster is specifically defined as smaller than that one: "Enthusiasts use the term to apply to a roller coaster with a drop of 300 to 399 feet, meaning that its riders fall the length of a football field. (Anything beyond 400 feet and you’re in strata coaster terrain.)" So yeah, weird article.